This invention relates to ties for use in maintaining a predetermined spaced relation between opposed forms prior to and during the pouring of a concrete wall therebetween. The invention is particularly concerned with "snap ties" which are designed to have their outer end portions broken off inside the wall after the concrete has set and the forms have been removed.
In the conventional use of snap ties, each tie has a shoulder or other spacer adjacent each end thereof which butts the inner surface of a form. The remainder of the tie passes through a hole in the form and has a head on its outer end which cooperates with clamping means and reinforcing lumber ("wales") to brace the assembled forms against the internal hydraulic pressure developed while the concrete suspension fills the space between the forms.
The present invention is concerned with a problem affecting the utility of snap ties of conventional construction which arises from the fact that during erection of the form and their reinforcing lumber, the mechanical connection between the head of each tie and the adjacent wale is provided by a wedge designed to apply tension to the end portion of each rod between each head and the spacer which engages the inner face of the adjacent form.
The problem to which the invention is directed is that with conventional ties and associated parts, instead of maintaining essentially axially directed tension on these end portions of each rod, forces are developed which apply a twisting force to one or both of the rod heads in the area where they interconnect with the remainder of the rod. These forces are often so severe as to cause the head of the rod to snap off prematurely, thereby reducing the holding force on the forms and making it possible for them to move apart, and thus to produce a wall of non-uniform thickness.